The ProxyJump, or the -J flag, was introduced in ssh version 7.3. To use it, specify the bastion host to connect through after the -J flag, plus the remote host:
ssh -J <bastion-host> <remote-host>
You can also set specific usernames and ports if they differ between the hosts:
ssh -J user@<bastion:port> <user@remote:port>
The ssh man (or manual) page (man ssh) notes that multiple, comma-separated hostnames can be specified to jump through a series of hosts:
ssh -J <bastion1>,<bastion2> <remote>
This feature is useful if there are multiple levels of separation between a bastion and the final remote host. For example, a public bastion host giving access to a "web tier" set of hosts, within which is a further protected "database tier" group might be accessed.